1. Field of the Invention
The present invention relates to an applicator for dental cement lining essential for the pulp protection prior to the tooth restoration, which makes it possible to precisely and rapidly line only the required region such as a deep floor in the proximal cavity with a lining material such as dental cement.
2. Statement of the Prior Art
Required for the restoration of defects in the tooth hard tissues are generally such treatments as indirect pulp capping intended to line an area with the pulp unexposed in a deep portion in the cavity floor with a lining material such as dental cement or direct pulp capping intended to protect a small area with the pulp exposed by lining of a material such as dental cement.
In general, applicators for dental cement lining are used for the treatment such as the indirect pulp capping or the direct pulp capping to be applied to the required region such as the deep portion in the cavity floor. Of these applicators, the one enjoying the most frequent use has its functional head in the form of a small sphere.
Such a prior art applicator for cement lining having a spherical head includes a shaft and a spherical portion provided at the extreme end thereof and having its center lying on a line extending axially therefrom. Hence, it appears that said applicator is easy to handle, since it theoretically permits lining of the cement material in every direction. In actual use, however, the spherical head is found to offer the following various problems.
In most cases, the applicator has its head put into a lining material for collection, so that the lining material is uniformly deposited on the entire head. This results in the following problems.
By way of example, explanation will now be made to the lining of a cement with respect to the axial cavity walls of proximal cavities in the anterior and posterior teeth.
(1) As illustrated by Area A in FIG. 11, the cement tends to be deposited on the unrequired region such as the adjacent tooth surfaces other than Area D to be lined, thus presenting a contamination phenomenon. Since the cement deposited on the adjacent tooth surfaces creates an obstacle to filling of a restoring material, it has to be completely removed in advance. This imposes extremely troublesome and extra manipulations upon a dentist.
(2) During the application of the cement, it is likely that a portion of the lining material deposited on the applicator may come into contact with cavity wall surfaces other than the required region, and remain there, as shown by Area B in FIG. 11. Since the portion of the lining material applied on the unrequired regions may be responsible for deteriorations of the adaptation, adhesion and marginal closure of the restoration to the cavity wall, they should be removed. This may lead to a considerable drop in working effeciency.
(3) The field of view may be blocked by a portion of the lining material deposited on the face of the applicator's head opposite to its available face, as depicted by Area C in FIG. 11, thus leading to a failure in precise lining of the required region with the lining material. Especially, such a phenomenon occurs in the treatment of proximal cavities.
(4) In most cases, the portion of the lining material deposited on the face of the applicator's head opposite to its available face is disposed without use. Thus, wasteful consumption of the material is very likely to result.
(5) Due to the fact that the spherical portion of the head of the applicator is as small as 1 mm at the most, it is difficult to control the amount of the lining material to be collected.